The radial condition
\(w=w(\vert t\vert )\)  leads to another, quite different, interpretation of equation (REF ): it
is the condition that a certain meromorphic connection \(\hat{\alpha }\)  in the variable \(\lambda \in \ast \) 
has the property that its monodromy data is independent of \(z\) . Details of this formulation
can be found in section 2 of [1]}.
